1. Field of the Invention
The present invention relates to a improvement in copying machines such as electrophotographic copying machines wherein the distance of the projection scanning for the original is variable.
The projection scanning of an original as stated in the specification of the present invention, means the exposure scanning obtained from the relative movement between a copy board for holding the original to be copied and an optical means including an illuminating lamp to project an image of the original onto a drum, specifically for example, onto the photosensitive layer on the surface thereof. Therefore, it is independent of whether the copy board is movable type or fixed type; accordingly, the present invention can be applied to either type described above.
2. Description of the Prior Art
In a conventional copying machine wherein the distance of the projection scanning for the original, i.e., the traveling distance of the optical system (for convenience' sake, the optical system means the illuminating lamp here) in the fixed type copy board for example, is variable, an arrangement has been employed wherein when the size of the copy paper or transfer paper (hereinafter referred to simply as papers) is A4 or B5 (FIG. 1), papers are fed in the feeding direction of the shorter side thereof, while in case the size of paper is A3 or B4, papers are fed in the feeding direction of the longer side thereof. Namely, though there has been a certain relation between the original to be placed on the copy board and papers to be used for said original (imagining the case that the copy board and the path for papers are in parallel leads to a prompt understanding). In case of copying with a one-to-one magnification, for example, when papers to be used are fed in the direction of the corresponding width thereof for the width of the original when viewed in the direction perpendicular to the direction of the traveling path of said papers, the ways of placing such papers on the copy board have been different from one another according to the size of the original. The distance of projection scanning, in case the size of the original is A4 or B5, has been made the same as the shorter side of A4 size, and in case the size of the original is A3 or B4 has been made the same as the longer side of A3 size, and thus has been made changeable in two steps. In such a copying machine, in spite of the requirement to increase the copying speed for the large size paper such as A3, B4, it is not easy, due to the limitation of mechanical and electrical control, to meet the requirement for high speed copying which has recently been desired without lowering the image quality and the stability of the device, even if an increase in the operating speed of the entire copying machine is possible. Such controlling method or original placement method has been determined from the view point of ease of operation, and such method has been effected with little trouble since no consideration for the function of reduction and enlargement has been taken. However, when it is desired that such device is given the function of reduction and enlargement, the weak point thereof becomes clearly disclosed, including the damage extending to the shape of the cassette. For example, if it is possible for the conventional copying machine to make even a variable magnification copying as stated above, for the difference between the case of one-to-one magnification projection copying and the case of variable magnification projection copying, the complication that the direction of placing on the copy board should be changed even for the same size original, or the direction of papers to be used should be changed with same direction of placing the original, is disclosed. Namely, in case the original of A3 size is copied on the paper of A3 size with a one-to-one magnification for example, the direction of placing of the original is equated with the feeding direction of papers of A3 size, but in case the original of A3 size is copied on the A4 size paper with a reduction, the direction of the placing of the original should be equated with the feeding direction of the A4 size paper. Otherwise, problems that copied images do not appear or an extreme margin is produced on one side may happen. On the contrary, when the original of A3 size is placed in the same manner as the one-to-one magnification copying, the feeding direction of the A4 size paper should be changed to the direction that is the same as in the case of one-to-one magnification copying wherein A3 size papers are used, in order to prevent the occurrence of the above-mentioned problems. Namely, in case of one-to-one magnification copying, the direction of the shorter side of the A4 size paper is the feeding direction thereof and when the original of A3 size is copied onto the A4 size paper with reduction, the direction of the longer side of the A4 size paper should be the feeding direction thereof. By doing that, the weak point that not only the device becomes complicated concerning the supply of the paper but also the handling thereof is troublesome, is produced. Inconvenience caused by the relative relation between the original and the paper in the conventional copying machine mentioned above will also result even for the case wherein the projection copying with an enlargement is made.